Referring initially to FIG. 1, there is shown a conventional wireless communication system 100. The system 100 includes at least one wireless transmit/receive unit (WTRU) 102, an access point 104, and at least one system controller 106 for controlling and otherwise managing communications within the system 100. Typically, in wireless local area network (WLAN) type systems, the network may be deployed as shown in FIG. 2.
In FIG. 2, the wireless network 200 comprises a system controller 206, a plurality of access points 214, 216, and a plurality of WTRUs 212, 218. WTRUs 212, 218 are grouped with there respective access points 214, 216. These groupings are commonly referred to as basic service sets (BSSs) 220, 222. A plurality of BSSs 220, 222 are typically connected via a distribution system (DS) 224 wherein a plurality of BSSs are commonly referred to as an extended service set (ESS). The access points 214, 216 are preferably connected to the system controller 206 over a network 219.
Generally, assistance data is data provided, or otherwise accessible at a particular access point, to WTRUs associated with the particular access point. Typically, assistance data may include any type of data relating to any type of information related to access points neighboring the particular access point (i.e. access points whose respective coverage areas are adjacent to the coverage area of the particular access point). Providing assistance data facilitates ring/handover of WTRUs by providing essential information regarding finding/identifying neighboring access points.
By way of example, assistance data may include information regarding neighboring access points such as operational frequency of neighboring WTRUs and access points, access modes [e.g. 802.11 Frequency Hopping Spread Spectrum (FHSS)/Direct Sequence Spread Spectrum (DSSS), 802.11a, 802.11b High Rate Direct Sequence Spread Spectrum (HR-DSSS), etc.], timing, system configuration information regarding neighboring basic service sets (BSSs) [e.g. ready to send (RTS)/clear to send (CTS), Point Coordination Function (PCF), Wired Equivalent Privacy (WEP), etc.].
Currently, assistance data is transmitted using point-to-point (i.e. unicast) signaling. In 802.xx type systems, for example, the assistance data is provided in the form of an Information Element (IE) containing neighbor information. The IE is incorporated into the existing Probe Response frame. The Probe Response frame is typically sent by an access point as a reply to a Probe Request management frame sent by a WTRU when the WTRU is attempting to discover neighboring BSSs. This arrangement is inefficient, however, in that transmitting assistance data using point-to-point signaling results in significant amounts of network traffic thereby significantly increasing the likelihood of significant delays not only with respect to transmission/reception of the assistance data, but also with respect to transmissions/receptions generally.
It would therefore be desirable to provide a method and system for providing WTRUs with assistance data without the limitations discussed above.